1. Field of the Invention
The present invention relates generally to materials lifting apparatuses, and more particularly, but not by way of limitation, to an improved pipe handling apparatus for transporting pipe between a pipe storage rack and a rig floor which is elevated above the pipe storage rack.
2. Brief Description of the Related Art
In the drilling of a well, tubular members such as drill pipe, casing, and production tubing must be transported between a pipe storage rack and a drilling rig floor. For instance, it is necessary periodically to pull the drill string out of the well bore (“tripping out”) to replace the drill bit and in turn run the drill string back into the well bore. This process involves a series of repetitive steps in which joints of pipe are withdrawn from the well bore, disconnected, and stored on the pipe storage rack. The process is then repeated in reverse order to replace the drill string in the well bore. Due to the fact that the drilling rig floor can be as much as 20 to 30 feet above ground level, numerous devices have been previously proposed to assist in the movement of the tubular members between the pipe storage rack and the rig floor. Such devices are generally complex in construction, designed for use with a particular drilling rig, and not easily transported from one drilling rig to another.
As with the drilling process, the servicing of a well involves a series of repetitive steps to replace production tubing or maintenance downhole equipment. Rigs used for servicing wells are often referred to as “workover” rigs. Workover rigs generally have a rig floor positionable over the surface equipment of the well and a mast which supports the elevators. The elevators are used to raise and lower the production tubing into and out of the well bore and to handle the individual joints of pipe once they are on the rig floor.
The rig floor of a workover rig can be elevated as much as 6 to 15 feet above ground level depending on the amount of surface equipment utilized with the well. However, unlike with drilling rigs, it has been the practice to manually transport the pipe between the rig floor and the pipe rack. This involves a worker rolling a joint of pipe off the pipe rack onto a platform known as a “catwalk.” The worker then drags the pipe toward the rig and raises one end of the pipe toward the rig floor to the point where the elevators of the rig can latch onto the end of the pipe. The process is reversed when removing pipe from the rig. This practice is extremely labor intensive, time consuming, and dangerous.
To this end, a need exists for an improved pipe handling apparatus which is simple in construction, easy to transport and operate, and which is adapted to be used with a variety of different rigs. It is to such an apparatus that the present invention is directed.